<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>

        td{
            width: 200px;
            text-align: center;
            height: 30px;
        }
        [colspan]{
            background: red;
        }

        select, button {
            height: 30px;
        }
        input{
              height: 24px;
          }

        div{
            margin-bottom: 5px;
        }
    </style>
</head>
<body>

    <div class="top1">
        <select>
            <option>美元</option>
            <option>人民币</option>
            <option>欧元</option>
        </select>
        <button>互换</button>
        <select>
            <option>美元</option>
            <option>人民币</option>
            <option>欧元</option>
        </select>
        <span>数额:</span>
        <input>
        <button>汇率换算</button>

    </div>
    <table border="1">
        <tr>
            <td colspan="3">按当前汇率换算结果</td>
        </tr>
        <tr>
            <td>美元</td>
            <td>汇率</td>
            <td>人民币</td>
        </tr>
        <tr>
            <td>100</td>
            <td>6</td>
            <td>600</td>
        </tr>
    </table>

</body>
</html>
